optfc foramen 

 frontal 



parietal 



squamosal 



lacrimal 

 nasal 



orbitonosol fissure 

 postparretal 



fenestro dorsalis 



prefaciol commissure 



olo temporalis \ orbitoporietol commissure 

 Ola orbitalis \ \ \ parietocopsulor fissure 



parietal lamina 



occipitocopsulor fissure 

 fenestra cochleae Meckel's cartilage' 



mandibular cartilages 



malleus part of Meckel's cartilage 



nasal 



endolymphatic foramen 



D 



nasal septum 



foramen epiphaniale jf"; 

 cribriform plate, 

 orbitonasal fissure. 



optic foramen, 

 dorsum selloe 



ola temporalis 



basicochleor 



fenestra 



hiatus faciali; 



frontal 



preoptic pillar 



foramen prechiasmoto 

 ala hypochiasmota 

 metoptic pillar 



carotid foramen 

 alicochlear commissure 



internal auditory meatus 



parietal 



squamosal 



postporietol 



maxilla, 

 infraorbital foramen 



I'ugal 

 polatii 

 pterygoid, 

 squamosal. 



Meckel's cartilage 



dentary. 

 tympanic 



malleus 

 fenestra cochleae 



hypoglossal foramina 

 postporietol 



palatine process 

 poraseptol cartilage 

 ethmoturbinol I 



lamina tronsversolis 

 posterior 



pterygoid process 



.carotid foramen 



mandibular 

 cartilages 



hyoid 



stapes 



mastoid process 



synotic and posterior tectum 

 Figure 3-14. Chondrocranium and early ossifications in the hare, lepus cun/cu/us. (After Voit, 1909) 



jugular foramen 

 foramen magnum 



be perforated by the maxillary branch of the trigeminal 

 nerve (i.e. in the latter instance lying between the maxil- 

 lary and mandibular branches). The posterior basicochlear 

 fissure may be confluent with the jugular foramen as it is in 

 some placentals. There may be three separate pairs of 

 hypoglossal foramina. The preoptic pillar may attach to the 

 lamina orbitonasalis through its ala minima rather than with 

 the trabecula. The lamina transversus posterior of the nasal 

 capsule may be present, along with the anterior lamina, 

 and is connected with the paraseptal cartilage. 



The marsupial hyoid and branchial cartilages are like 

 those of the placental; the second and third ceratobranchial 

 form the thyroid cartilage. 



Alonofreme The fully formed chondrocranium of Ormtho- 

 rhynchus (Figure 3-15) has well-developed side walls and a 

 broad tectum posterior, which includes a connection between 

 the parietal plates called the synotic tectum. The occipital 

 condyles are large and the otic capsules are completely con- 

 nected with the side walls. There is no hypoglossal foramen 



DEVELOPMENT OF THE HEAD SKELETON • 55 



